The present specification generally relates to systems for and methods of increasing the location accuracy (e.g., geographic location accuracy). More particularly, the present specification relates to increasing location and/or targeting accuracy using an image product.
It is desirable to increase location and/or targeting accuracy in a variety of systems. An example of a system that could benefit from increased location and/or targeting accuracy is a system that uses a synthetic aperture radar or other battlefield image products.
Military planners and campaigners heretofore have not achieved the full capacity of airborne synthetic aperture radar (SAR) implemented on unmanned aerial vehicles (UAV). One large advantage of UAV SAR systems in a tactical environment is their relatively low cost, flexibility of deployment, useful resolution (˜0.25 m), and all weather and day/night imaging capability. A significant disadvantage of UAV SAR systems is lower geographic location accuracy of targets within their field of view.
One measure of munition capability is the circular error probable (CEP) or radius from the mean impact location it lands 50% of the time. R95 is a factor proportional to CEP and represents the radius from the mean landed in 95% of the time. These are measures of munition repeatability. Kill radius (Rk) sets the combined munition/target area in which the designated target is destroyed if it lands within this area. For hard targets (tanks, bunkers, etc), Rk is a strong function of position on the target. Target ‘soft spots’ have larger Rk values while physically missing the target aim point by much at all leads to a zero kill radius (Rk=0).
For a soft target (unarmored vehicle, standard building, antenna, etc), Rk is a very weak function of position. FIG. 1 shows Rt/R95 v. Rk/R95 where targeting inaccuracy Rt=offset of mean landing point of munition from intended position, is achieved. A curve 1 in FIG. 1 describes the ability to destroy targets. Rt is the maximum allowed targeting error to destroy a soft target for a given kill radius Rk. Both axes in FIG. 1 are scaled by the munition repeatability, R95.
The plot of curve 1 is largely linear with Rt/R95˜Rk/R95−0.83 for Rk/R95>1.2. Since soft targets are usually destroyed by energetic shrapnel whose energy incident on a unit area ˜1/R^2, the minimum munition weight is ˜Rk^2.
FIG. 2A shows the munition weight required for a given targeting error (W(Rt)) relative to the weight for zero targeting error (W(0)). For a targeting error (Rf) equal to half of the munition R95 (Rt/R95=0.5), the weight is 60% more than minimum weight but a targeting error double the R95 (Rt/R95=2) requires 640% over the minimum as shown by the plot of curve 2. The ability to effectively attack targets with lighter munitions means a given weapons platform (e.g., missile carrying drone) can carry a greater number of munitions and potentially destroy a greater number of targets.
Munitions designed for attacking hard targets generally penetrate the target to some depth followed by an explosion. To accomplish this, the munition must land within some distance (Rs) from the soft spot and no further away. Increasing the explosive power does not by much increase Rs. In this case, the maximum allowed targeting error (Rt) relative to R95 is still given by curve 1 in FIG. 1 only the x-axis scale is interpreted as Rs/R95 instead of Rk/R95. In all cases, Rt<Rs meaning the targeting error must be less than the target size (soft spot size) if the target is to be successfully destroyed.
If targeting capability limits the ability to achieve high kill probabilities, multiple munitions per target can be launched. However, launching multiple munitions per target is costly. The targeting probability can be taken as uniform within a circle of radius Rt centered on the aim point and the size of the target soft spot is Rs. Plots of curves 3, 4, 5 and 6 in FIG. 2B show the maximum targeting error for a given number of munitions (nmun) required to hit a hard target within its soft spot. As an example, a target with a soft spot twice the size of the munition repeatability (Rs/R95=2) can be hit using a single munition (nmun=1) with 95% probability if the maximum targeting error is <=1.6*R95 but if the targeting error exceeds 2.75*R95, over 4 munitions (nmun=4) are required for the same probability of success. Most of the advantage of using multiple munitions can be obtained with nmun=2; the returns rapidly diminish beyond this as shown by curves 3, 4, 5 and 6. The ability to significantly increase targeting accuracy (decrease Rt) leads to fewer instances where multiple munitions are required to destroy a designated target.
Submeter accuracy today is generally achieved by active man-in-the-loop continuous adjustment (“joy sticking”) of the munition trajectory. This requires personnel and aircraft to remain in the proximity of the munition drop off point. Achieving high Pk's (kill probabilities) in this manner places high value assets (aircraft and personnel) at greater risk than attacking from a larger standoff distance and immediately leaving the munition drop off point. A further drawback of joy sticking for accuracy is that a single munition requires the full attention of the bombardier for the duration of the drop (˜1 minute). This precludes attacking multiple targets in parallel with the same high precision.
Thus, there is a need to increase targeting and/or location accuracy. There is also a need to increase targeting accuracy for a UAV. There is also a need for a UAV SAR with greater geographic accuracy. There is further a need for precision target geographic location utilizing a lower accuracy immediate image product. There is a further need for improving aircraft navigational fix using an image product for location determination. There is further a need for a system and method of increasing location or targeting accuracy using a remapping technique.